DISSERTATION RESEARCH: How do plant genetics, soil microbes and the environment determine plant and soil function across global change gradients?

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How well plants weather changes to their environment and the success of plants in new environments will depend not only on their genetics but also on interactions with soil organisms. Knowing how plant genetics relates to growth in stressful conditions, and whether soils contain "friends or foes" that improve or reduce plant growth is key to predicting the future success or failure of environmentally and economically important plants. This project will explore how plant genetics and soil organisms (bacteria and fungi) can help plants perform well where they are now or help them in new sites if their current environment becomes more stressful. This project builds on 15 years of research demonstrating genetic links between plants, soil organisms and soil fertility in different types of places. These genetic links maintain the diversity of plants and soil organisms and determine how energy flows through ecosystems at large scales. The results will provide land managers fundamental insights into how trees respond to environmental stresses, such as rising temperatures, longer and more severe droughts, and nitrogen pollution. Identification of soil organisms that influence plant health will be applicable to a wide range of environmental change issues. The study will provide training in diverse lab and field techniques and opportunities to develop independent research projects to several undergraduate students. With the rapid rate of environmental change, plant populations that are well adapted to sites today are likely to be locally maladapted in the future. As stress causes plant populations to adapt or migrate to more favorable habitats, predicting adaptation will rely on understanding patterns of genetic diversity, while migrations will be determined by factors that influence species range dynamics. Since plants experience multiple abiotic and biotic environments simultaneously that affect their performance, it is critical to study genetic resources under realistic conditions that incorporate interacting species such as soil bacteria, fungi, and archaea (i.e., the soil microbiome). Current research shows that genetic variation in plant-soil-microbiome linkages will dictate how above- and belowground systems respond to global change. The goal of this study is to discover plant genetic and soil microbiome mechanisms that allow or impede plant adaptation and migration in response to environmental change. To achieve this, the project will conduct a greenhouse experiment to characterize plant genetic-soil microbe-abiotic environment interactions along experimental gradients of temperature, water availability, and soil nitrogen based on previous field surveys. Researchers will measure plant and soil responses across the gradients, plant-soil conditioning effects, and soil community effects on ecologically important plant traits. In addition, they will identify specific combinations of plant genotypes, soil microbiomes, and abiotic environments that result in nonadditive effects on plant productivity and nutrient dynamics. This approach will provide insight for ecological feedbacks that are important to: 1) non-additive responses of plants to abiotic stressors; 2) the maintenance of plant genetic variation and soil microbial phylogenetic diversity; and 3) resilience and stability of soil nutrient pools (e.g., C and N).